Secret key is not verified in scotty example

[kvanbere]

Operating system or device, package version, compiler version:
All

Issue description:
In the scotty example (examples/scotty) the key specified by KEY= on launch is not verified. If the incorrect key is specified on GitHub the example server doesn't care. This is a security risk and means that the scotty example should not be used in production.

Note: This is not applicable to the servant example(s), which verify the keys correctly.

[kvanbere]

This has been bumped to a higher priority.

[kvanbere]

We would very much like to deliver this with 0.16.0 because of its security content.
Help wanted.